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New HyperThreading Flaw Affects Intel 6th And 7th Generation Skylake and Kaby Lake-Based Processors (hothardware.com)
MojoKid writes: A new flaw has been discovered that impacts Intel 6th and 7th Generation Skylake and Kaby Lake-based processors that support HyperThreading. The issue affects all OS types and is detailed by Intel errata documentation and points out that under complex micro-architectural conditions, short loops of less than 64 instructions that use AH, BH, CH or DH registers, as well as their corresponding wider register (e.g. RAX, EAX or AX for AH), may cause unpredictable system behavior, including crashes and potential data loss. The OCaml toolchain community first began investigating processors with these malfunctions back in January and found reports stemming back to at least the first half of 2016.
The OCaml team was able pinpoint the issue to Skylake's HyperThreading implementation and notified Intel. While Intel reportedly did not respond directly, it has issued some microcode fixes since then. That's not the end of the story, however, as the microcode fixes need to be implemented into BIOS/UEFI updates as well and it is not clear at this time if all major vendors have included these changes in their latest revisions.
The OCaml team was able pinpoint the issue to Skylake's HyperThreading implementation and notified Intel. While Intel reportedly did not respond directly, it has issued some microcode fixes since then. That's not the end of the story, however, as the microcode fixes need to be implemented into BIOS/UEFI updates as well and it is not clear at this time if all major vendors have included these changes in their latest revisions.
AMD Ryzen also seems to have a similar bug, related to hyperthreading that happens only in very special circumstances.
Quite a few Ryzen users have experienced instability problems during heavy compilation loads under Linux, especially those using compile-based distros such as Gentoo, but also under the Ubuntu subsystem on Windows.
There has been some debate whether the problems would have been caused by an actual bug, or if the people who experienced them simply had an unstable overclock - the latter being something that has also cropped up in forums recently.
Matthew Dillon, of Dragonfly BSD fame (and Amiga fame before that...) does believe that he has found a reproducible bug. He sent a test case about it to AMD in April.
This is not the first time Dillon has found a hardware bug in a AMD CPU. He found one for an earlier AMD CPU back in 2012 which was fixed in a microcode update.
I expect this to be fixed in a BIOS/microcode update soon, if not already in AGESA 1.0.0.6 - but I have yet to see any confirmation that it would have been fixed.
"We mustn't be caught by surprise by our own advancing technology" -- Aldous Huxley
All you losers with your over-priced Intel crap.
I've used nothing but AMD for 20 years and I have absolutely no probl%#^$^%J NJasllodofufm DUDFUF&&()()FDJJDNDMS .......
If you don't know the model name of your processor(s), the command below will tell you their model names. Run it in a command line shell (e.g. xterm): /proc/cpuinfo | sort -u
grep name
C:\>grep name /proc/cpuinfo | sort -u
'grep' is not recognized as an internal or external command, operable program or batch file.
C:\>